[kenjackson]

Probably some amount. I agree Windows is strategic, but do definitely could see them giving it away and/or fully open sourcing it.

[pjmlp]

It is most likely impossible, given the amount of code that is probably still under contractors copyright, or other kinds of licenses.

[rswail]

They don't have to provide the source to give the OS away for free.

The difference between BSD and GPL in one sentence.